1. Technical Field
The present invention relates to a method of producing metal nanoparticles, in particular, to a method of producing metal nanoparticles with the solution method.
2. Description of the Related Art
Major ways to produce metal nanoparticles are the vapor-phase method and the solution (colloid) method. Since the vapor-phase method which uses plasma or gas evaporation requires highly expensive equipments, the solution method which is easy for the production is generally used.
A method of producing metal nanoparticles by the solution method up to now is to dissociate a metal compound in a hydrophilic solvent and then apply a reducing agent or a surfactant to produce metal nanoparticles in the form of hydrosol. Another method is the phase transfer method, which produces metal nanoparticles by transferring a compound from a hydrophilic solvent to a hydrophobic solvent to produce metal nanoparticles which are dispersed in the hydrophobic solvent. However, the production of metal nanoparticles by this existing method provides a very low yield rate, as it is limited by the concentration of the metal compound solution. That is, it is possible to form metal nanoparticles of uniform size only when the concentration of the metal compound is less than or equal to 0.05M. Thus, there is a limit also on the yield of metal nanoparticles, and to obtain metal nanoparticles of uniform size in quantities of several grams, 1000 liters or more of functional group are needed. This represents a limitation to efficient mass production. Moreover, the phase transfer method necessarily requires a phase transfer, which is a cause of increased production costs.
Approaches to solve such existing problems and to produce high yield rate of metal nanoparticles with uniform size are in progress.